The present invention relates to a method of making a gear and mounting it on a shaft or a hub.
A gear, generally, is comprised of a wheel or disc and a gear or toothed rim. It is common practice to weld the wheel or disc to the rim as well as to the shaft, axle or hub. The teeth are, usually, milled, tempered (hardened) and ground or polished. The known manufacturing methods proceed as follows.
At first, the rim part is welded to the wheel, and the latter is thereafter welded to the hub or shaft. Next, the teeth are cut into the rim by milling. If the rim was already tempered, the gear is completed. However, it is quite impractical to mill after tempering. Moreover, in the specific practice to be improved by this invention, the welded and milled gear (including shaft or axle) is placed into a furnace for tempering, and the tempered gear is finally ground and, possibly, polished.
There is nothing basically wrong with that process of making a gear except that the combination of a shaft with a gear has quite a disadvantageous geometric configuration. Usually the shaft is considerably longer than the width of the teeth, the tempering furnace must be dimensioned to accommodate the assembly as to the entire shaft length, whatever that length happens to be. In reality, this constitutes a considerable waste in furnace space.
In view of the fact that the shaft or hub is also placed into the tempering furnace, one has to cover the bearing seats at the shaft ends or one may have to cover the interior of the hub in order to avoid inclusion of carbon. Alternatively, the shaft seats have to be ground later, e.g., when the teeth are ground. However, the latter grinding operation is quite different from the former, so that special machines are needed for grinding the shaft seats. Moreover, the shafts carry the gear at that time so that one cannot even use regular shaft grinders, because the respective gears are an impediment.